added chart to topics, added similar page to articles

...nd/src/main/java/de/vipra/rest/resource/InfoResource.java

vipra-cmd/src/main/java/de/vipra/cmd/lda/DTMAnalyzer.java

vipra-ui/app/html/about.html

vipra-ui/app/html/articles/show.html

vipra-ui/app/html/articles/similar.html

vipra-ui/app/html/topics/show.html

vipra-ui/app/js/app.js

vipra-ui/app/js/controllers.js

vipra-util/src/main/java/de/vipra/util/Constants.java